The present invention relates to unsubstituted and substituted poly(9,9xe2x80x2-spirobisfluorenes); a process for their preparation; a composition comprising a support material and a layer of an unsubstituted or substituted poly(9,9xe2x80x2-spirobisfluorene), which may, if desired, further comprise a luminophore; a composition comprising an unsubstituted or substituted poly(9,9xe2x80x2-spirobisfluorene) which comprises a luminophore; and the use of the compositions or the poly(9,9xe2x80x2-spirobisfluorenes) as fluorophores, for example in light-emitting diodes or electrodes in display applications, and also 2,2xe2x80x2-dihalo-7,7xe2x80x2-disubstituted 9,9xe2x80x2-bisfluorenes.
In recent times, materials which emit fluorescent radiation have attracted greatly increased interest for display elements or photodiodes. In Adv. Mater. 1994, 6, No. 3, pages 190 to 198, J. M. Tour describes polyphenylenes which are known to emit blue fluorescent light. The good mechanical and thermal properties of the polyphenylenes are known. The insolubility in organic solvents and the associated unsatisfactory processibility and also the instability of doped polyphenylenes greatly impairs commercial utilization. There is a great need for blue-fluorescing and processible materials based on aromatic hydrocarbons, which materials have excellent thermal and mechanical properties (for example thermal stabilities above 200xc2x0 C.); the polymers should be able to be prepared easily and, in particular, the targeted preparation of defined polymers should be possible. Furthermore, it is desirable for the polymers to be suitable as matrix for the incorporation of small amounts of different fluorophores in order to obtain fluorescent emissions over the entire visible spectrum.
It has now surprisingly been found that 9,9xe2x80x2-bisfluorenes can be polymerized to give blue-fluorescing polymers which are soluble in many solvents and are therefore also readily processible, for example by means of customary coating processes. The polymers have excellent thermal and mechanical stabilities and are excellent matrix systems for the incorporation of molecular fluorophores which can be used in fluorescent displays and in electroluminescent displays.
The invention provides, firstly, soluble poly(bis-9,9xe2x80x2-fluorenes) comprising identical or different structural repeating units of the formula I, 
where
the two R1s are, independently of one another, H, C1-C18alkyl, C6-C14aryl, C7-C15aralkyl, C1-C18alkoxy, R2xe2x80x94(Oxe2x80x94CnH2n)mxe2x80x94Oxe2x80x94, C1-C18alkylthio, C1-C18dialkylamino, xe2x80x94C(O)OH, xe2x80x94C(O)Oxe2x80x94C1-C18alkyl, xe2x80x94C(O)xe2x80x94N(C1-C18alkyl)2, xe2x80x94SO3H, xe2x80x94SO3xe2x80x94C1-C18alkyl, xe2x80x94SO2xe2x80x94N(C1-C18alkyl)2, C1-C17alkyl -C(O)xe2x80x94Oxe2x80x94 or C1-C17alkyl-C(O)xe2x80x94, R2 is H or C1-C12alkyl, n is from 2 to 6 and m is from 1 to 12.
The alkyl groups in alkyl, alkoxy, alkylthio, diaminoalkyl, carboxylic ester or sulfonic ester, carboxamide or sulfonamide, alkyl-CO2xe2x80x94 and alkyl-C(O)xe2x80x94 radicals R1 can be linear or branched and preferably contain from 1 to 12, particularly preferably from 1 to 8, C atoms. Some examples of alkyl are methyl, ethyl, n- and i-propyl, n-, i- and t-butyl, and the isomers of pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, hexadecyl and octadecyl.
Aryl radicals R1 preferably contain from 6 to 10 C atoms. Some examples are naphthyl, biphenylyl and, particularly preferably, phenyl.
Aralkyl radicals R1 preferably contain from 7 to 12 C atoms and the alkylene group in the aralkyl radical preferably contains 1 or 2 C atoms. A preferred example is benzyl and also phenylethyl.
Halogen atoms R1 are preferably F, Cl or Br.
Alkyl radicals R2 preferably contain from 1 to 8 and particularly preferably from 1 to 4 C atoms. They can be linear or branched. Some examples are methyl, ethyl, n-propyl and n-butyl.
In the radical R2xe2x80x94(Oxe2x80x94CnH2n)mxe2x80x94Oxe2x80x94, n is preferably from 2 to 4, particularly preferably 2 or 3.
In the radical R2xe2x80x94(Oxe2x80x94CnH2n)mxe2x80x94Oxe2x80x94, m is preferably from 1 to 8, particularly preferably from 1 to 6.
In a preferred embodiment of the invention, the two R1s in the polymers of the formula I are identical radicals as defined above.
In a preferred embodiment of the invention, each R1 in the polymers of the formula I is H, C1-C12alkyl-C(O)xe2x80x94 or C1-C12alkoxy.
The polymers of the invention can be crosslinked, which depends essentially on the method of preparation. The degree of crosslinking can be so high that a virtually only crosslinked low molecular weight polymer, which is, however, still soluble, is obtained. Such polymers comprise structural units of the formula Ia, Ib or both structural units, 
where R1 is as defined above.
Structural units of the formula Ia are formed from monosubstituted 9,9xe2x80x2-bisfluorenes and structural units of the formula Ib are formed from unsubstituted 9,9xe2x80x2-bisfluorene.
The degree of polymerization (number of structural repeating units) can be from 2 to 100, more preferably from 3 to 50, even more preferably from 3 to 40 and particularly preferably from 5 to 30. The term polymers thus also encompasses oligomers. In general, the polymers of the invention comprise polymer chains having different degrees of polymerization (chain lengths).
The polymers of the invention can be prepared by methods known per se and by methods analogous to those described in the literature.
The invention further provides a process for preparing poly(bis-9,9xe2x80x2-fluorenes) comprising identical or different structural repeating units of the formula I, 
and, if desired, identical or different structural units of the formulae 
where R1 is as defined above, which process comprises cationically-oxidatively polymerizing a) at least one halogen-free 9,9xe2x80x2-bisfluorene of the formula II, 
where R1 is as defined above,
in the presence of an inert solvent.
Examples of suitable solvents are N,N-disubstituted carboxamides and N-substituted lactams (dimethylformamide, N-methylpyrrolidone), esters (butyl acetate), ethers (dibutyl ether), sulfoxides (dimethyl sulfoxide), sulfones (tetramethylene sulfone), aliphatic and aromatic hydrocarbons (toluene, xylene), halogenated or nitrated aliphatic and aromatic hydrocarbons (carbon tetrachloride, tetrachloroethane) and carbon disulfide.
The cationic-oxidative polymerization has been described for benzene by P. Kovacic et al. in Tetrahedron Letters No. 11, pages 467 to 469 (1962) and can also be employed analogously for the polymerization of 9,9xe2x80x2-spirobisfluorenes.
The polymerization is carried out, for example, using oxidizing Lewis acids such as FeCl3 or using Lewis acids, mainly metal halides such as AlCl3, AlBr3, BF3 or BCl3, in combination with an oxidizing agent such as a metal compound having a relatively high oxidation state. Use is frequently made of CuCl2. Oxidizing agents such as KMnO4, Fe+3 salts and benzoquinone derivatives such as tetrachlorobenzoquinone can also be used. It is also possible to employ electrochemical oxidation in a suitable organic solvent for effecting the polymerization.
The molar ratio of spirobisfluorene to catalyst or Lewis acid can be from 1:0.2 to 1:2, preferably from 1:0.4 to 1:1.5 and particularly preferably from 1:0.5 to 1:1.2. The molar ratio of Lewis acid to oxidizing agent can be, for example, from 1:0.2 to 1:1, preferably from 1:0.3 to 1:0.8 and particularly preferably from 1:0.4 to 1:0.6.
The reaction temperature is preferably from 200xc2x0 C. to 200xc2x0 C., more preferably from 20xc2x0 C. to 150xc2x0 C., particularly preferably from 20xc2x0 C. to 100xc2x0 C. and most particularly preferably from 30xc2x0 C. to 80xc2x0 C.
The reaction can be carried out, for example, by adding the catalyst to the dissolved spirobisfluorene, if desired heating the mixture and allowing it to react for some time (for example up to 24 hours) while stirring. The polymer formed can then be precipitated and filtered off or the solvent can be removed. To remove the Lewis acids/oxidizing agents, the residues can be washed with water, dried and then treated with solvents such as methylene chloride or tetrahydrofuran to isolate the desired soluble polymers.
In this polymerization method, crosslinked polymers are frequently formed and insoluble polymers can easily be removed. The degree of crosslinking can be influenced by the reaction conditions, for example the monomer concentration in the reaction mixture, the amount of catalyst and the ratio of catalyst to oxidizing agent, and by the reaction temperature.
Another way of preparing the polymers of the invention is from 2,2xe2x80x2-halogenated 9,9xe2x80x2-spirobisfluorenes using a method similar to that described by T. Yamamoto et al. in Bulletin of the Chemical Society of Japan, Vol. 51 (7), pages 2091 to 2097 (1978) and Macromolecules 25, pages 1214 to 1223 (1992). This method is preferred since polymers having a defined structure can be prepared in a targeted manner.
The invention also provides a process for preparing poly(bis-9,9xe2x80x2-fluorenes) comprising identical or different structural repeating units of the formula I, 
where R1 is as defined above, which process comprises reacting a 2,2xe2x80x2-dihalo-9,9xe2x80x2-spirobisfluorene of the formula III, 
where R1 is as defined above and X is halogen,
in the presence of an inert solvent, an alkali metal or alkaline earth metal and a transition metal complex or metal salt of a transition metal.
X is preferably F, Cl or Br, more preferably Cl or Br and particularly preferably Br.
Suitable solvents are mainly the solvents used for Grignard reactions, for example aromatic hydrocarbons such as benzene, toluene, xylene, nitrobenzene and ethers such as diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane, ethylene glycol diethyl ether, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether.
As alkali metals and alkaline earth metals, use is frequently made of Li, Na, K, Zn, Cd, Mg and Ca; particular preference is given to Li and Mg.
A great many suitable transition metal complexes are known. The transition metal complexes can be those of metal ions or uncharged metals. Some examples of metals are Fe, Co, Ni, Mo, Cr, W and noble metals such as Pt, Pd, Ru, Ir and Os. In the case of metal ion complexes, the anions can be derived from inorganic or organic acids, for example acetic acid, benzoic acid, toluenesulfonic acid, sulfuric acid and hydrohalic acids. Preference is given to metal halide complexes. Examples of uncharged ligands are open-chain and cyclic 1,3-dienes (cyclohexadiene, cyclooctadiene), nitriles (acetonitrile and benzonitrile), ethers, alcohols, tertiary phosphines (triphenylphosphine and tricyclohexylphosphine), ditertiary diphosphines, tertiary amines and ditertiary diamines such as bipyridine. Some examples of metal complexes are Ni(cyclooctadiene)2 in admixture with P(C6H5)3, Ni[P(C6H5)3]4, NiCl2(bipyridine)2, NiBr2[P(C6H5)3]2, Pd(Cl)2(bipyridine)2, NiCl2, CoCl2, FeCl2 and FeCl3.
The amount of alkali metals or alkaline earth metals is preferably equimolar to the amount of dihalo-9,9xe2x80x2-spirobisfluorene, but a slight excess can also be used. The amount of transition metal complexes or transition metal salts is preferably likewise equimolar, but a slight excess or deficiency can be used.
The reaction can take place even under mild conditions at room temperature. A higher temperature of, for example, up to 150xc2x0 C., preferably up to 100xc2x0 C., accelerates the reaction.
The polymerization can be carried out by combining the reaction components with the solvent, then heating the mixture and allowing it to react to completion. To avoid excessively long induction times, a small amount of elemental iodine, for example, can be added. The reaction can also be carried out by first preparing the corresponding organometallic compound (Grignard compound) from the dihalo-9,9xe2x80x2-spirobisfluorene and an alkali metal or alkaline earth metal or a corresponding metal alkyl and only then adding a transition metal complex.
The polymers can be isolated in a customary manner, for example by filtering off insoluble constituents of the reaction mixture, washing to remove salts, precipitation or removing the solvent. The polymers can be purified by reprecipitation and, if appropriate, washing.
Some of the compounds of the formula II are known or they can be prepared by methods known per se.
2,2xe2x80x2-Dibromo-9,9xe2x80x2-spirobisfluorene can be prepared by direct bromination of 9,9xe2x80x2-spirobisfluorene in the presence of Lewis acids such as FeBr3 (V. Prelog et al., Helvetica Chimica Acta 52(5), page 4253 (1969). The resulting product mixtures of compounds having different degrees of bromination and positional isomers can be purified by recrystallization and chromatographic methods. 2,2xe2x80x2-Dinitro-9,9xe2x80x2-spirobisfluorene can be prepared by the method of J. Weissenburger, JACS, page 4253 (1950) and isolated in pure form from the product mixture by recrystallization and chromatographic methods. The dinitro compound can, for example, be reduced using iron in ethanol to give the diamine, then diazotized and reacted with CuBr to form 2,2xe2x80x2-dibromo-9,9xe2x80x2-spirobisfluorene.
2,2xe2x80x2-Diamino-9,9xe2x80x2-spirobisfluorene can be converted into the corresponding N,N,Nxe2x80x2,Nxe2x80x2-tetraalkyl compounds by means of alkylating agents. The reaction of the dibromo compounds with organometallic hydrocarbon compounds (Grignard compounds) leads to the dialkyl or diaryl derivatives. Substitution with alcohols, thiols or polyoxaalkylenediol monoethers gives the alkoxy-, alkylthio- and polyoxaalkylenoxy-substituted derivatives.
Diazotized 2,2xe2x80x2-dinitro-9,9xe2x80x2-spirobisfluorene can be converted by means of concentrated sulfuric acid into 2,2xe2x80x2-dihydroxy-9,9xe2x80x2-spirobisfluorene which can be esterified in a manner known per se. 2,2xe2x80x2-Dimethyl-9,9xe2x80x2-spirobisfluorene can be oxidized in a customary manner to give the carboxylic acid and then esterified or amidated. 9,9xe2x80x2-Spirobisfluorene-2,2xe2x80x2-sulfonic acid is obtainable in a known manner by oxidation of 9,9xe2x80x2-spirobisfluorene-2,2xe2x80x2-dithiol, with the dithiol being obtainable by nucleophilic substitution of 2,2xe2x80x2-dibromo-9,9xe2x80x2-spirobisfluorene.
2,2xe2x80x2-Diacyl-9,9xe2x80x2-spirobisfluorenes can be obtained in a simple manner and in high yields by Friedel-Crafts acylation using carboxylic acid halides in the presence of Lewis acids such as AlCl3.
It has surprisingly been found that the dihalo compounds of the formula III are obtained in high yields and regioselectivity from the compounds of the formula I in which R1 is not a hydrogen atom if the reaction is carried out using elemental halogen, for example Cl2, Br2 or I2, preferably Br2, in the presence of an excess of a Lewis acid.
The invention further provides compounds of the formula IV, 
where
X is halogen and
R3 is C1-C18alkyl, C6-C14aryl, C7-C15aralkyl, C1-C18alkoxy, R2xe2x80x94(Oxe2x80x94CnH2n)mxe2x80x94Oxe2x80x94, C1-C18alkylthio, C1-C18dialkylamino, xe2x80x94C(O)OH, xe2x80x94C(O)Oxe2x80x94C1-C18alkyl, xe2x80x94C(O)xe2x80x94N(C1-C18alkyl)2, xe2x80x94SO3H, xe2x80x94SO3xe2x80x94C1-C18alkyl, xe2x80x94SO2xe2x80x94N(C1-C18alkyl)2, C1-C17alkyl-C(O)xe2x80x94Oxe2x80x94 or C1-C17alkyl-C(O)xe2x80x94, R2 is H or C1-C12alkyl, n is from 2 to 6 and m is from 1 to 12.
X is preferably Cl, Br or I, more preferably Cl or Br, and particularly preferably Br.
For R3, the preferences and preferred embodiments given for R1 in formula I apply.
The invention also provides a process for preparing the compounds of the formula IV, which comprises reacting a compound of the formula V, 
where R3 is as defined above, in an inert solvent with elemental halogen in the presence of an excess of a Lewis acid.
The reaction temperature can be from room temperature to 200xc2x0 C., preferably from 20 to 100xc2x0 C. and particularly preferably from 20 to 50xc2x0 C. The reaction is particularly preferably carried out at room temperature, which may require cooling at the beginning of the reaction.
The halogen is preferably used in equimolar amounts.
Suitable solvents are polar aprotic solvents which can be used alone or in mixtures. Some examples are open-chain or cyclic ethers, carbon disulfide and halogenated aliphatic or cycloaliphatic hydrocarbons.
Examples of suitable Lewis acids are BF3, BCl3, AlBr3, AlCl3, ZnCl2, ZnBr2, FeCl2, FeCl3, FeBr2, FeBr3, TiCl4, TiBr4, SnCl2, SnBr2, SnCl4 and SnBr4. Preference is given to using AlCl3or AlBr3.
Excess can mean that the Lewis acids otherwise used in catalytic amounts in halogenation reactions of aromatics are present in an amount of at least 1 mol, preferably at least 2 mol, more preferably at least 4 mol and particularly preferably at least 10 mol, based on 1 mol of the compound of the formula V.
The isolation of the desired compounds and their purification can be carried out in a customary manner; purification itself is often not necessary since by-products are formed only in small amounts. The compounds of the invention are, depending on substitution, crystalline or amorphous solids which are soluble in polar aprotic solvents and are therefore readily processible. Even the monomers have a bluish fluorescence and are well suited to preparing defined and generally uncrosslinked polymers.
Despite the stiff structural units, the polymers of the invention are still soluble in customary organic solvents and can therefore be used and readily processed in solution as coating materials. They have very high thermal stabilities, glass transition temperatures and excellent mechanical properties. Furthermore, the poly(bis-9,9xe2x80x2-fluorenes) of the invention have absorption bands in the wavelength region below about 400 nm, and fluorescence emission maxima at wavelengths of from about 420 to 460 nm. They are thus blue-fluorescing materials which have been provided for the first time as processible polymers.
The invention further provides a composition comprising (a) a solvent and (b) a poly(bis-9,9xe2x80x2-fluorene) having identical or different structural repeating units of the formula I.
The amount of dissolved poly(bis-9,9xe2x80x2-fluorene) depends essentially on the solvent, the degree of polymerization and crosslinking and the substitution. The solutions according to the invention can contain from 0.01 to 80% by weight, preferably from 0.01 to 60% by weight, more preferably from 0.01 to 50% by weight, particularly preferably from 0.1 to 30% by weight and very particularly preferably from 0.1 to 20% by weight, of poly(bis-9,9xe2x80x2-fluorene, based on the total amount of the composition.
The composition of the present invention can comprise further additives, for example processing aids, agents for improving the mechanical and thermal properties, agents for improving the appearance or agents for improving the adhesion properties. Some examples are fluidizers, or adhesion promoters, dyes, pigments, heat stabilizers and light stabilizers, antistatics, antioxidants, lubricants, mold release agents, fillers, reinforcing fillers and viscosity-increasing substances.
In a particularly preferred embodiment, the composition of the invention (solution) further comprises at least one fluorescent dye (fluorophore). Preference is given to those fluorescent dyes whose absorption band overlaps the emission band (fluorescent emission) of the polymer of the invention. The amount of additional fluorescent dye can be, for example, from 0.000001 to 10% by weight, preferably from 0.00001 to 5% by weight, more preferably from 0.0001 to 3% by weight, particularly preferably from 0.001 to 3% by weight and very particularly preferably from 0.001 to 2% by weight, based on the amount of polymer. Many such dyes are known. Some examples are rhodamines, fluoresceins, cumarins, distyrylbiphenyls, stilbenes, phthalocyanines, naphthalocyanines, metal complexes of transition metals and lanthanide metals. It is also possible to use fluorescent latent pigments (solubilized pigments having solubilizing substituents such as detachable protective groups) selected from the group consisting of diketopyrrolopyrroles or quinacridones, fluorescent perylene derivatives or fluorescent perinones. It is likewise possible to use commerical products such as Lumogen L Yellow(copyright), Brilliant Yellow(copyright), Yellow Orange(copyright) or Red Orange(copyright) (BASF) and also 2,2xe2x80x2-dihydroxybipyridyls and related compounds. Molecularly dispersed (dissolved) fluorescent pigments can also be used. Such compositions are obtainable by dissolving pigments solubilized by means of protective groups in the polymer of the invention and subsequently splitting off the protective group, for example by heating.
The composition (solution) of the invention can be processed in molds with removal of the solvent, if desired with application of vacuum, to produce free-standing moldings and films. The polymers obtained can be doped with, for example, iodine or salts such as alkali metal hexafluorometalates and used as electric conductors, for example as electrodes. The solutions are of particular importance for coating support materials.
The invention furthermore provides a support material which is coated on at least one side with a polymer according to the invention.
In a preferred embodiment, the polymer layer comprises at least one further fluorophore dispersed homogeneously in the polymer layer; the emission band of the polymer preferably overlaps the absorption band of the fluorophore. By means of the content of additional fluorophores, all colors of the visible spectrum can be generated by selection of different emissions in the visible region, with the polymer itself having a blue fluorescence. This blue basic fluorescence can be reinforced by blue-emitting fluorophores or modified. The preferred amounts and some selected fluorophores have been indicated above.
A great number of support materials are known. The support material can be an inorganic or organic support material. The support material can be opaque, translucent or transparent. Preference is given to transparent support materials. Examples of suitable support materials are plastics, glass, cermics, minerals, rocks, metal oxides and metal mixed oxides, metal nitrides, metal carbides, semiconductors, transparent electric conductors (for example ITO-glass, glass supports coated with SnO2/In2O3), metals and metal alloys.
The luminescence of the polymers of the invention and their mixtures with fluorophores can also be stimulated by electric conductors (electrofluorescence). A particularly advantageous embodiment of the invention is therefore an electroluminescent composition comprising an electric conductor as support material which is coated on at least one side with a polymer according to the invention either alone or in admixture with at least one additional fluorophore. The coating is preferably connected to a counterelectrode which is particularly preferably transparent.
The electric conductors can, depending on the application, be opaque, translucent or transparent and be semiconductors or metallic conductors. Transparent conductors are preferably glasses coated with semiconducting metal oxides or mixtures of metal oxides.
The thickness of the polymer layer can be, for example, from 0.1 to 1000 xcexcm, preferably from 1 to 500 xcexcm and particularly preferably from 10 to 200 xcexcm.
The coated support material can be produced in a manner known per se by dipping, painting or casting processes, particularly spin coating, with the thickness of the layer being able to be determined by means of the content of polymer and, if used, fluorophore in the solution and also by selection of the process conditions.
The polymers and coated support materials of the invention can be used wherever markings by means of fluorophores are to be detected or decorative effects are to be achieved. The coated electric conductors can be used particularly advantageously as light-emitting diodes for the entire visible spectrum. Transparent, coated electrodes are also suitable for VDUs or display elements of electronic image reproduction systems.
The invention further provides for the use of the polymers, if desired additionally doped with at least one further fluorophore, of the invention as active radiative layer for light-emitting diodes, VDUs and display elements.